Microplastic (MP) contamination has become a problem of great interest to the community at large. The detection of these particles in different ecosystems and foods has been the subject of study. ...However, the focus of these investigations has been on the identification and quantification of PM by DSC and Pyr-GC/MS and not on how they are transported to reach the air we breathe. In this study, the values of morphological parameters for plastic particles in a range between 1 and 2000 µm, present in the breathable air of 20 neighborhoods in the city of Cartagena, Colombia, were obtained to determine the characteristics that make these particles airborne. The values of parameters were obtained, such as roundness, sphericity, curvature, and the convexity of the particle, as well as its compactness and size, which influence its transport through the air and its ability to be ingested and inhaled. The data obtained in this study allows for simulations and the analysis of the behavior of microplastics once in the environment to predict future settlements. The DSC showed us the melting temperatures of PP, PE, PET, and PS, the Pyr-GC/MS showed the fragmentation patterns, and the presence of these MPs in the samples was confirmed.
For the synthesis of polymeric resins, it is of great importance to review the raw materials and the equipment to be used to avoid the presence of compounds that may affect the effectiveness of the ...polymerization and the characteristics of the plastic to be obtained. Iron oxide is a compound that can be present in reactors after maintenance due to the techniques used and the cleaning of this equipment, and it can affect the characteristics of the resins, reducing their quality. In this study, the presence of FeO in different concentrations was evaluated to determine its effects on the properties and pyrolysis of polypropylene resins by using X-ray refraction to determine the elements of the samples, evaluating thermal degradation by TGA, the variation in molecular weight by measuring the MFI, and the compounds obtained from pyrolysis by chromatography. The results showed that the thermal degradation decreased as the FeO concentration increased, while for the MFI, the relationship was directly proportional. The evaluation of the compounds obtained from pyrolysis showed an increase in the production of alcohols, alkynes, ketones, and acids, and a decrease in alkanes and alkenes, showing that FeO affects the properties of polypropylene and the compounds that are produced during pyrolysis.
The copolymer synthesis process can be affected by failures in the production process or by contaminating compounds such as ketones, thiols, and gases, among others. These impurities act as an ...inhibiting agent of the Ziegler-Natta (ZN) catalyst affecting its productivity and disturbing the polymerization reaction. In this work, the effect of formaldehyde, propionaldehyde, and butyraldehyde on the ZN catalyst and the way in which it affects the final properties of the ethylene-propylene copolymer is presented by analyzing 30 samples with different concentrations of the mentioned aldehydes along with three control samples. It was determined that the presence of formaldehyde 26 ppm, propionaldehyde 65.2 ppm, and butyraldehyde 181.2 ppm considerably affect the productivity levels of the ZN catalyst; this effect increases as the concentration of aldehydes is higher in the process; likewise, these impurities affect the properties of the final product, such as the fluidity index (MFI), thermogravimetric analysis (TGA), bending, tension, and impact, which leads to a polymer with low-quality standards and less resistance to breakage. The computational analysis showed that the complexes formed by formaldehyde, propionaldehyde, and butyraldehyde with the active center of the catalyst are more stable than those obtained by the ethylene-Ti and propylene-Ti complexes, presenting values of -40.5, -47.22, -47.5, -5.2 and -1.3 kcal mol
respectively.
Mid‐infrared laser spectroscopy was used to investigate common bacteria encountered in biopharmaceutical industries. The study involved the detection of bacteria using quantum cascade laser ...spectroscopy coupled to a grazing angle probe (QCL‐GAP). Substrates similar to surfaces commonly used in biopharmaceutical industries were used as support media for the samples. Reflectance measurements were assisted by Multivariate Analysis (MVA) to assemble a powerful spectroscopic technique with classification and identification resources. The species analyzed, Staphylococcus aureus, Staphylococcus epidermidis, and Micrococcus luteus, were used to challenge the technique's capability to discriminate from microorganisms of the same family. Principal Components Analysis and Partial Least Squares‐Discriminant Analysis differentiated between the bacterial species, using QCL‐GAP‐MVA as the reference. Spectral differences in the bacterial membrane were used to determine if these microorganisms were present in the samples analyzed. Results herein provided effective discrimination for the bacteria under study with high sensitivity and specificity.
A quantum cascade laser coupled to a Grazing Angle Probe produced high‐quality spectral information from Staphylococcus aureus, Staphylococcus epidermidis, and Micrococcus luteus. Although the bacteria under investigation belong to the same family, the spectral information was robust enough to discriminate the bacteria mixtures from the neat bacteria.
One route of exposure to SPAs is through bottled water since the polymers used to make plastic bottles contain these SPAs, which migrate from the plastic to the water. Solid-phase extraction (SPE), ...HPLC-MS, FTIR, and DSC are used to identify and quantify these SPAs in water. Interday measurements of cyanox 1790 in water with HPLC showed RSD, error, and R2 lower than 3.78, 9.3, and 0.99995, respectively. For intraday measurements of cyanox 1790 in water, the RSD, error, and R2 were less than 4.1, 11.2, and 0.99995, respectively. Concentrations of Cyanox 1790 in water from non-recycled bottles ranged from 0.01 ± 0.0004 to 4.15 ± 0. 14 ppm, while the levels of cyanox 1790 in water in recycled bottles ranged between 0.01 ± 0.0005 and 11.27 ± 0.12 ppm. In the tests carried out, an increase in the migration of Cyanox 1790 from plastic bottles to water was identified, since the ppm of Cyanox increased in the water as the days of storage increased at 40 °C.
In the present work, four (4) samples of sylvite (KCl) from different deposits in Canada, Belarus and Germany were analyzed in order to determine the differences between them in terms of chemical ...composition, morphology and impurities present. Different non-instrumental and instrumental techniques were used. A scanning electron microscope analysis showed that the particles are completely amorphous. Bueno mineral has particles with the largest area (with 91.4% particles larger than 0.50 mm), and the BPC mineral samples have those with the smallest area (with 49.9% particles smaller than 0.50 mm). The Bueno mineral has the highest angle of repose. Bueno mineral has the highest surface area and pore volume when compared to the other KCl minerals. On the other hand, the BPC KCl mineral presented a lower surface area and pore volume. The problem mineral has the highest percentage composition of K. Blanco mineral did not present Al, and the element Mo was not detected in the Blanco and Bueno mineral. The IR bands of O-H, C-N, N-H and C=O bonds were observed. These results are useful for the fertilizer industry. These differences can produce adverse effects in a subsequent application in fertilizer production processes. Such differences can be attributed to the origin of this mineral, the way it is obtained and exploited, or to the transport and storage process through the use of anticompacting additives due to the high hygroscopicity of the mineral.
This work aimed to study the removal of mercury from industrial wastewater, using activated carbon from Hass avocado seed. The seed was carbonized to obtain activated carbon. Orthophosphoric acid at ...21% w/v was used as an activating agent. The Hg2+ concentration was determined by atomic absorption spectroscopy. The chemical surface of the material was performed by Fourier transform infrared spectroscopy. The carbons were morphologically characterized using a scanning electron microscope. The conditions of the experiments were 50 mL of industrial wastewater at room temperature, pH 6.0, initial concentration of mercury 0.036 mgL-1 and 0.2 gL-1 of adsorbent material. The average removal efficiency of activated carbon (CA) for Hg2+ was 84% and an equilibrium concentration of 0.006 mgL-1 after 60 minutes. Two kinetic models and one diffusion model were applied. The model that best describes the adsorption process was the Elovich model with an R2 of 0.9897. Results show that the seed of Persea americana is useful for obtaining carbon and becomes a good alternative to use in industrial wastewater treatments for the removal of Hg2+, turbidity, color, and total solids.
The process analytical technology (PAT) initiative proposed by the US Food and Drug Administration (FDA) suggests innovative methods to better understand pharmaceutical processes. The development of ...analytical methods that quantify active pharmaceutical ingredients (APIs) in powders and tablets is fundamental to monitoring and controlling a drug product’s quality. Analytical methods based on vibrational spectroscopy do not require sample preparation and can be implemented during in-line manufacturing to maintain quality at each stage of operations. In this study, a mid-infrared (MIR) quantum cascade laser (QCL) spectroscopy-based protocol was performed to quantify ibuprofen in formulations of powder blends and tablets. Fourteen blends were prepared with varying concentrations from 0.0% to 21.0% (w/w) API. MIR laser spectra were collected in the spectral range of 990 to 1600 cm−1. Partial least squares (PLS) models were developed to correlate the intensities of vibrational signals with API concentrations in powder blends and tablets. PLS models were evaluated based on the following figures of merit: correlation coefficient (R2), root mean square error of calibration, root mean square error of prediction, root mean square error of cross-validation, and relative standard error of prediction. QCL assisted by multivariate analysis was demonstrated to be accurate and robust for analysis of the content and blend uniformity of pharmaceutical compounds.
This work deals with the comparison of the theoretical assignment of the DADP vibrational spectrum with the experimental displacements by isotopic labeling. For this, the DADP-C4 and DADP-C2 ...isotopomers were synthesized from acetone labeled isotopically in the methyl and the carbonyl carbon atoms, respectively. The acetone and DADP-isotopomer compounds were characterized using Raman and infrared spectroscopy. Theoretical assignments were taken from previous studies on the potential energy distribution of a vibrational mode, which provide an approach to the internal coordinates related to each band. The selective isotopic labeling allowed us to approach to the dependence of each band, because the energy of a molecular vibration also depends on the reciprocal mass of the atoms involved. In general, the results showed that some bands assigned experimentally do not coincide with the theoretical assignments by quantum mechanical simulations.
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